CN201114936Y - Lamp drive circuit - Google Patents

Abstract

The utility model provides a lamp driving circuit, comprising a first lamp, a transformer and a detection unit. The transformer has a magnetic core, a primary coil and a first secondary coil. The primary coil is coupled to a control unit and receives a control signal from the control unit. One end of the first secondary coil is coupled to the first lamp. The detection unit is coupled to the magnetic core and the control unit. When the detection unit detects that the potential of the magnetic core changes, the detection unit sends a signal to the control unit, so that the control unit stops sending the control signal to the primary coil.

Description

Lamp drive circuit

technical field

The utility model relates to a lamp tube drive circuit, in particular to a lamp tube drive circuit with a detection unit.

Background technique

In the known technology, the design of the inverter (Inverter) is developed from a single transformer driving a single lamp to a single transformer driving multiple lamps. Generally, in the circuit design of the double-sided printed circuit board (PCB), the inverter adopts the method of capacitor voltage division to realize the mechanism of abnormal protection of the lamp tube. In the circuit design of the single-sided printed circuit board, the low-voltage side of the secondary coil of the transformer is used as the mechanism for abnormal protection of the lamp tube.

With the demand of market cost, the design of the inverter has been developed into a way that a single transformer drives multiple lamps, and the protection circuit for abnormal lamps needs to be more simplified. However, if the capacitive voltage division method is still used as the mechanism for abnormal protection of the lamp tube, the high-cost high-voltage capacitor and the design of the high-voltage circuit on the printed circuit board will increase the cost of the entire driving circuit.

Aiming at the deficiencies in the known technology, the utility model provides a lamp tube drive circuit, which effectively reduces the cost of the drive circuit components and reduces the high-voltage capacitor space required in the design of the printed circuit board.

Utility model content

The purpose of this utility model is to provide a lamp tube driving circuit, which has a detection unit that can detect the potential change of the magnetic core of the transformer, and send a signal according to the potential change.

In one embodiment, the lamp driving circuit includes a first lamp, a transformer, a control unit and a detection unit. The transformer has a magnetic core, a primary coil and a first secondary coil. The primary coil is coupled to the control unit and receives control signals from the control unit. The first secondary coil is coupled with the first lamp tube. The detection unit is coupled to the magnetic core and the control unit. When the first lamp tube is disconnected or short-circuited, the detection unit detects that the potential of the magnetic core changes, and the detection unit sends a signal to the control unit, so that the control unit stops sending control signals to the primary coil.

Another object of the present invention is to provide a lamp driving circuit, which has a detection unit to detect potential changes of multiple secondary coils and magnetic cores of the transformer, and send a signal according to the potential changes.

In another embodiment, the lamp driving circuit includes four lamps (the first lamp to the fourth lamp), a transformer, a control unit and a detection unit. The transformer has a magnetic core, a primary coil, a first secondary coil, and a second secondary coil. The primary coil is coupled to the control unit and receives control signals from the control unit. The primary coil, the first secondary coil and the second secondary coil are wrapped on the magnetic core respectively. The first secondary coil and the primary coil have a magnetic circuit, and the two ends are respectively coupled with the first lamp tube and the second lamp tube. The second secondary coil has the same winding number and magnetic circuit as the first secondary coil, and the two ends are respectively coupled with the third lamp tube and the fourth lamp tube. When at least one of the first lamp tube to the fourth lamp tube is open-circuited or short-circuited, the first secondary coil or the second coil causes the magnetic core potential of the transformer to change. The detection unit detects the potential change of the magnetic core, and sends a signal to the control unit, so that the control unit stops sending the control signal to the primary coil.

Combining the description of the following preferred embodiments and the accompanying drawings, the purpose, embodiments, features, and advantages of the present utility model will become clearer.

Description of drawings

FIG. 1A is a schematic diagram of a lamp driving circuit disclosed in an embodiment of the present invention;

Fig. 1B is a specific explanatory diagram illustrating Fig. 1A in an embodiment of the present invention;

Fig. 1C is a specific explanatory diagram illustrating Fig. 1A in an embodiment of the present invention;

Fig. 2A is a schematic diagram showing a lamp driving circuit disclosed according to another embodiment of the present invention;

Fig. 2B is a specific explanatory diagram illustrating Fig. 2A in another embodiment of the utility model; and

Fig. 3A is a schematic diagram showing the specific implementation of the lamp driving circuit disclosed in the utility model; and

FIG. 3B is a schematic diagram showing another specific implementation of the lamp driving circuit disclosed in the present invention.

Description of reference symbols

10 multi-lamp drive circuits

110 transformer

111 primary coil

112 first secondary coil

312 second secondary coil

113 core

113a core middle section

120 first light tube

140 control unit

141 input terminal

142 outputs

143 signal input terminal

150 detection units

160 winding frame

220 second lamp

310 third lamp

320 fourth lamp

Detailed ways

Referring to FIG. 1A , it is a schematic diagram of a lamp driving circuit 10 disclosed in an embodiment of the present invention. In this embodiment, the multi-lamp driving circuit 10 includes a transformer 110 , a first lamp 120 , a control unit 140 and a detection unit 150 . The transformer 110 also includes a primary coil 111 , a first secondary coil 112 and a magnetic core 113 . For example, the primary coil 111 and the first secondary coil 112 are wound on the magnetic core 113 . The first light tube 120 is coupled to the first secondary coil 112 . For example, the first lamp 120 can be a discharge lamp or other suitable lamps. The control unit 140 includes an input terminal Vi141 , an output terminal 142 and a signal input terminal 143 , the output terminal 142 is coupled to the primary coil 111 , and the control unit 140 sends a control signal to the primary coil 111 through the output terminal. One end of the detection unit 150 is connected to the signal input end 143 of the control unit 140 , and the other end is coupled to the magnetic core 113 of the transformer. For example, the detection unit 150 is coupled to the magnetic core 113 by a wire.

In this embodiment, a stray capacitance effect will be generated between the primary coil 111 of the transformer 110 and the first secondary coil 112 and the magnetic core 113 . For example, when the first light tube 120 on the first secondary coil 112 changes, due to the different output energy, through the stray capacitance effect, the magnetic core 113 will generate different potential differences according to the output load change. . In this embodiment, one terminal of the detection unit 150 generates a signal through the change of the potential on the magnetic core 113 . For example, the detection unit 150 is a potential detector, which can detect the change of the potential on the magnetic core 130 and then generate a signal. The signal generated above is sent to the signal input terminal 143 of the control unit 140 , so as to stop sending the control signal to the primary coil 111 . For example, the control unit 140 can be a pulse-width modulator (Pulse-width Modulation).

Referring to FIG. 1B , it is a schematic diagram illustrating an embodiment of FIG. 1A . In this embodiment, the first secondary coil 112 and the coupled first light tube 120 are in an open circuit state, for example, the first light tube 120 is burnt out. Since the first lamp tube 120 is in an open circuit state, the energy output by the first secondary coil 112 changes, and the potential of the magnetic core 113 changes according to the stray capacitance effect. For example: according to the state of the first lamp being disconnected, the potential of the magnetic core 113 is increased. The detection unit 150 transmits a signal to the signal input terminal 143 of the control unit 140 according to the potential change of the magnetic core 113 . In this way, the control unit 140 stops sending the control signal to the primary coil 111 .

Referring to FIG. 1C , it is a schematic diagram illustrating an embodiment of FIG. 1A . In this embodiment, the first secondary coil 112 and the coupled first lamp tube 120 are in a short-circuit state, for example, the first lamp tube 120 is short-circuited by a conductive object. Because the first lamp tube 120 presents a short-circuit state, the energy output by the first secondary coil 112 changes, and the potential of the magnetic core 113 is changed according to the stray capacitance effect, for example: according to the state of the first lamp short-circuit, the magnetic core 113 potential decrease. The detection unit 150 transmits a signal to the signal input terminal 143 of the control unit 140 according to the potential change of the magnetic core 113 . In this way, the control unit 140 stops sending the control signal to the primary coil 111 .

Referring to FIG. 2A , it is a schematic diagram of a lamp driving circuit 20 disclosed in another embodiment of the present invention. In this embodiment, the multi-lamp driving circuit 20 includes a transformer 110 , a first lamp 120 , a second lamp 120 , a control unit 140 and a detection unit 150 . The transformer 110 further includes a primary coil 111 , a first secondary coil 112 , a magnetic core 113 and a bobbin 160 . The bobbin 160 is disposed outside the magnetic core 113 . The primary coil 111 and the first secondary coil 112 are wound on the magnetic core 113 . The first light tube 120 is coupled to one end of the first secondary coil 112 . For example, the first lamp 120 can be a discharge lamp, or any other suitable lamp. The second lamp tube 220 is coupled to the other end of the first secondary coil 112 . For example, the second lamp 120 is a discharge lamp. The control unit 140 includes an input terminal Vi141 , an output terminal 142 and a signal input terminal 143 . One end of the detection unit 150 is connected to the signal input end 143 of the control unit 140 , and the other end is coupled to the magnetic core 113 of the transformer. For example, the detection unit 150 uses a wire to couple to the magnetic core 113, and the wire is arranged between the winding frame 160 and the magnetic core 113 of the transformer, so that the wire is sandwiched between the winding frame 160 and the magnetic core 113 , to ensure stable coupling between the wire and the magnetic core 113 .

Referring to FIG. 2B , it is a schematic diagram illustrating another embodiment of the utility model shown in FIG. 2A . In this embodiment, the first secondary coil 112 and the coupled first light tube 120 are in an open circuit state, for example, the first light tube 120 is burnt out. Since the first lamp tube 120 is in an open circuit state, the energy output by the first secondary coil 112 changes, and the potential of the magnetic core 113 is changed according to the stray capacitance effect, for example: according to the state of the first lamp short circuit, the magnetic core The potential of 113 increases. The detection unit 150 transmits a signal to the signal input terminal 143 of the control unit 140 according to the potential change of the magnetic core 113 . In this way, the control unit 140 stops sending the control signal to the primary coil 111 .

If the first secondary coil 112 and the coupled second lamp 220 are in a short-circuit state, for example, the second lamp 220 is short-circuited by a conductive object. Because the second lamp tube 220 presents a short-circuit state, the energy output by the first secondary coil 112 changes, and the potential of the magnetic core 113 is changed according to the stray capacitance effect, for example: according to the state of the second lamp short-circuit, the magnetic core 113 potential decrease. The detection unit 150 transmits a signal to the signal input terminal 143 of the control unit 140 according to the potential change of the magnetic core 113 . In this way, the control unit 140 stops sending out the control signal to the primary coil 111 .

Those skilled in the art should understand that regardless of whether the first lamp tube 120 or the second lamp tube 220 presents an open circuit, a short circuit or a combination thereof, the magnetic core 113 of the transformer 110 will also be connected to the first lamp tube 120 according to the first secondary coil 112 . And/or the state of the second lamp tube 220 changes, thereby generating a potential change on the magnetic core 113, for example: according to the state change of the first lamp tube 120 and/or the second lamp tube 220, the potential on the magnetic core 113 increases or reduce. The increase or decrease of the potential on the magnetic core 113 does not limit the features of the present invention. In any case, as long as the potential on the magnetic core 113 is abnormal, the state change of the first lamp 120 and/or the second lamp 220 can be known. . That is, the abnormality of the potential on the magnetic core 113 makes the detection unit 150 send a signal to the control unit 140 , and then stops sending the control signal to the primary coil 111 .

Referring to FIG. 3A , it is a schematic diagram of a specific implementation of the lamp driving circuit 30 disclosed in an embodiment of the present invention. In this embodiment, the multi-lamp driving circuit 30 includes a transformer 110 , a first lamp 120 , a second lamp 220 , a third lamp 310 , a fourth lamp 320 , a control unit 140 and a detection unit 150 . The transformer 110 has a primary coil 111 , a first secondary coil 112 , a magnetic core 113 and a second secondary coil 312 . The first secondary coil 112 and the second secondary coil 312 are respectively located on two sides of the primary coil 111 . For example, the arrangement is first secondary coil-primary coil-second secondary coil. The first secondary coil 112 and the primary coil 111 form a first magnetic circuit, and the second secondary coil 312 and the primary coil 111 also form a second magnetic circuit identical to the first magnetic circuit. Two ends of the first secondary coil 112 are respectively coupled to the first light tube 120 and the second light tube 220 , and two ends of the second secondary coil 312 are respectively coupled to the third light tube 310 and the fourth light tube 320 . The control unit 140 includes an input terminal Vi141 , an output terminal 142 and a signal input terminal 143 . One end of the detection unit 150 is connected to the signal input end 143 of the control unit 140 , and the other end is coupled to the magnetic core 113 of the transformer. For example, the detection unit 150 is coupled to the magnetic core 113 by a wire.

Referring to FIG. 3B , it is a specific implementation schematic diagram of the lamp driving circuit 30 disclosed in another embodiment of the present invention. In this embodiment, the components are described as in FIG. 3A. The first secondary coil 112 and the primary coil 111 form a first magnetic circuit, and the second secondary coil 312 and the primary coil 111 also form a second magnetic circuit identical to the first magnetic circuit. Two ends of the first secondary coil 112 are respectively coupled to the first light tube 120 and the second light tube 220 , and two ends of the second secondary coil 312 are respectively coupled to the third light tube 310 and the fourth light tube 320 . The control unit 140 includes an input terminal Vi141 , an output terminal 142 and a signal input terminal 143 . One end of the detection unit 150 is connected to the signal input end 143 of the control unit 140 , and the other end is coupled to the magnetic core 113 of the transformer. For example, the detection unit 150 is coupled to the magnetic core 113 by a wire. The difference is that the first secondary coil 112, the primary coil 111 and the second secondary coil 312 are all wound on the middle section 113a of the magnetic core 113, and the arrangement is also the first secondary coil-primary coil-second secondary coil.

Similar to the aforementioned FIG. 2B , in this embodiment, no matter the first light tube 120 , the second light tube 220 , the third light tube 310 or the fourth light tube 320 . If at least one of the above-mentioned light tubes is in an open circuit or short circuit state, the energy output by the first secondary coil 112 or the second secondary coil 312 will be changed, and the potential of the magnetic core 113 will be changed according to the stray capacitance effect, for example: The potential of the magnetic core 113 is increased according to at least one of the above-mentioned lamps showing an open circuit. Those skilled in the art should understand that the increase or decrease of the potential on the magnetic core 113 does not limit the features of the present utility model. In any case, as long as the potential on the magnetic core 113 is abnormal, it can be known that the first lamp 120 to the fourth The state of any one of the lamps 320 changes. A signal is sent to the signal input terminal 143 of the control unit 140 through the detection unit 150 according to the potential change of the magnetic core 113 . The output of the control signal to the primary coil 111 can be stopped by the control unit 140 .

The above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the claims of the present utility model. Under the premise of not departing from the spirit and scope of the present utility model, all equivalent changes or modifications completed shall be Included in the claims of the utility model.

Claims (9)

1. lamp tube drive circuit is characterized in that it comprises:

One first fluorescent tube;

One transformer, this transformer have a magnetic core, a primary coil and one first secondary coil, and this primary coil couples a control unit, and receive a control signal of this control unit, and an end of this first secondary coil and this first fluorescent tube couple;

One detecting unit couples this magnetic core and this control unit;

When the current potential that detects this magnetic core when detecting unit changed, this detecting unit was sent a signal to this control unit, makes this control unit stop to send this and controls signal to this primary coil.

2. lamp tube drive circuit as claimed in claim 1 is characterized in that, wherein opens circuit or during short circuit, the current potential of this magnetic core changes when this first fluorescent tube.

3. lamp tube drive circuit as claimed in claim 1 is characterized in that, wherein this detecting unit utilizes a lead and this magnetic core to couple.

4. lamp tube drive circuit as claimed in claim 1 is characterized in that, wherein this first fluorescent tube comprises discharge lamp.

5. lamp tube drive circuit as claimed in claim 1 is characterized in that, also comprises one second fluorescent tube, and the other end of this first secondary coil and this second fluorescent tube couple.

6. lamp tube drive circuit as claimed in claim 1 is characterized in that, also comprises a second subprime coil and one the 3rd fluorescent tube, and this second subprime coil has identical coiling number with this first secondary coil, and an end of this second subprime coil couples the 3rd fluorescent tube.

7. lamp tube drive circuit as claimed in claim 6 is characterized in that, also comprises one the 4th fluorescent tube, and the other end of this second subprime coil and the 4th fluorescent tube couple.

8. lamp tube drive circuit as claimed in claim 6 is characterized in that, this first secondary coil and this second subprime coil lay respectively at the both sides of this primary coil.

9. lamp tube drive circuit as claimed in claim 3 is characterized in that, also comprises a drum stand, is arranged at the magnetic core outside, and this lead is sandwiched between this drum stand and the magnetic core.

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